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Merge pull request paperjs#944 from iconexperience/fix-getWinding
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Change the implementation of getWinding() again to pass all unit tests.
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@lehni
lehni committed Feb 5, 2016
2 parents 41aca10 + 5b31aee commit ec75985
Showing 1 changed file with 45 additions and 42 deletions.
87 changes: 45 additions & 42 deletions src/path/PathItem.Boolean.js
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Original file line number Diff line number Diff line change
Expand Up @@ -314,10 +314,10 @@ PathItem.inject(new function() {
py = point.y,
windLeft = 0,
windRight = 0,
isOnCurve = false,
length = curves.length,
roots = [],
abs = Math.abs;
abs = Math.abs,
isOnCurve = false;
// Horizontal curves may return wrong results, since the curves are
// monotonic in y direction and this is an indeterminate state.
if (horizontal) {
Expand Down Expand Up @@ -357,64 +357,67 @@ PathItem.inject(new function() {
values = curve.values,
yStart = values[1],
yEnd = values[7];
// The first curve of a loop holds the last curve with non-zero
// winding. Retrieve and use it here (See _getMonoCurve()).
// The first curve of a loop holds the last curve with
// non-zero winding.
// Retrieve and use it here (See _getMonoCurve()).
if (curve.last) {
// Get the end x coordinate and winding of the last
// non-horizontal curve, which will be the previous
// non-horizontal curve for first curve in the loop.
// non-horizontal curve for the first curve in the loop.
prevWinding = curve.last.winding;
prevXEnd = curve.last.values[6];
}
// Since the curves are monotone in y direction, we can just
// compare the endpoints of the curve to determine if the
// ray from query point along +-x direction will intersect
// the monotone curve.
// Horizontal curves with winding == 0 will be completely
// ignored.
if (winding && (py >= yStart && py <= yEnd
|| py >= yEnd && py <= yStart)) {
// Calculate the x value for the ray's intersection.
var x = py === yStart ? values[0]
: py === yEnd ? values[6]
: Curve.solveCubic(values, 1, py, roots, 0, 1) === 1
if (py >= yStart && py <= yEnd || py >= yEnd && py <= yStart) {
if (winding) {
// Calculate the x value for the ray's intersection.
var x = py === yStart ? values[0]
: py === yEnd ? values[6]
: Curve.solveCubic(values, 1, py, roots, 0, 1) === 1
? Curve.getPoint(values, roots[0]).x
: null;
if (x != null) {
// If the point is between the curve's start point and
// the previous curve's end point, it must be on a
// horizontal curve in between.
var isOnHorizontal =
py === yStart && (px - x) * (px - prevXEnd) < 0;
// Test if the point is on a y-monotonic curve
if ((x >= xBefore && x <= xAfter) || isOnHorizontal)
isOnCurve = true;
// Count the intersection of the ray with the
// y-monotonic curve if:
// - the crossing is not the start or end of the curve
// - or the crossing is at the start of the curve and
// the winding did not change between curves
if (py != yEnd
&& (py != yStart || winding === prevWinding)) {
if (x < xBefore) {
windLeft += winding;
} else if (x > xAfter) {
windRight += winding;
if (x != null) {
// determine if the point is on the horizontal
// connection between the last non-horizontal curve's
// end point and the current curve's start point
var isOnHorizontal =
(py === yStart && (px - x) * (px - prevXEnd) < 0);
// Test if the point is on the current monocurve
if (x >= xBefore && x <= xAfter) {
isOnCurve = true;
// Count the intersection of the ray with the
// monotonic curve if:
// - the crossing is not the start of the curve
// except if the winding changes.
// - and the point is not on the curve or on the
// horizontal connection between the previous
// curve and the current curve
} else if ((py != yStart || winding !== prevWinding)
&& !isOnHorizontal) {
if (x < xBefore) {
windLeft += winding;
} else if (x > xAfter) {
windRight += winding;
}
}
}
// Update previous winding and end coordinate whenever
// the ray intersects a non-horizontal curve.
prevWinding = winding;
prevXEnd = values[6];
// Test if the point is on the horizontal curve
} else if ((px - values[0]) * (px - values[6]) <= 0) {
isOnCurve = true;
}
// Update previous winding and end coordinate whenever
// the ray intersects a non-horizontal curve.
prevWinding = winding;
prevXEnd = values[6];
}
}
}
// If the point is on a monotonic curve, ensure that the winding is odd
// by applying bit-wise or `| 1` to the bigger absolute winding number:
// If winding is an even number and the point is on a curve, this will
// add up to the next uneven number, otherwise it remains the same.
return Math.max(abs(windLeft), abs(windRight)) | (isOnCurve ? 1 : 0 );
// If the point was on a monocurve, we are on the path by definition.
// In this case ensure that the winding is at least 1.
return Math.max(abs(windLeft), abs(windRight), isOnCurve ? 1 : 0);
}

function propagateWinding(segment, path1, path2, monoCurves, operator) {
Expand Down

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